NITRATE IN GROUNDWATER ASSOCIATED WITH AGRICULTURAL SYSTEMS

Authors: Burkart, Michael; STONER, JEFFREY - USGS

Submitted to: American Geophysical Union
Publication Type: Proceedings
Publication Acceptance Date: 12/12/2003
Publication Date: 12/12/2003
Citation: BURKART, M.R., STONER, J.D. NITRATE IN GROUNDWATER ASSOCIATED WITH AGRICULTURAL SYSTEMS. AMERICAN GEOPHYSICAL UNION. 2003. CD-ROM. WASHINGTON, DC.

Interpretive Summary:

Technical Abstract: Data from the U.S.G.S. NAWQA program confirm hypotheses about the hydrologic and agricultural factors useful for defining spatial trends in groundwater vulnerability to nitrate contamination. Unconfined aquifers are most vulnerable to nitrate contamination with unconsolidated aquifers more vulnerable than carbonate aquifers. Where overlain by permeable soils, the probability of contamination increases as it does under irrigation. A system of corn/soybeans/hogs produced significantly larger nitrate concentrations than others. Nitrate concentrations under dairy, poultry, cattle and grains, and horticulture systems were similar. Irrigation, particularly in corn/soybean/hogs and horticulture systems, produced consistently larger nitrate concentrations in the NAWQA data as well as in studies from outside the U.S. Temporal trends in Asia and South America, similar to those experienced in the U.S. during recent decades, include increased inorganic fertilizer use, expansion of irrigated land, concentrated livestock production, and reduced reliance on organic fertilizer sources. These trends may be reflected in increased frequency of excess groundwater nitrate related to similar conditions in the U.S. The reduction of inorganic fertilizer use in Western and Eastern Europe as well as Russia during the last decade may warrant targeted monitoring to determine if excess nitrate contamination can be reduced. Expanded monitoring and research in Asia is warranted to determine if water-quality patterns observed in the U.S. irrigated areas are repeated there.